1. Field of the Invention
The present invention is generally in the field of electrical circuits and systems. More specifically, the present invention is in the field of power conversion and regulation in electrical circuits and systems.
2. Background Art
Voltage regulators are used in a variety of electronic circuits and systems. Many integrated circuit (IC) applications, for instance, require conversion of a direct current (DC) input signal to a lower, or higher, DC output. For example, a buck converter may be implemented as a voltage regulator to convert a higher voltage DC input to a lower voltage DC output for use in low voltage applications in which relatively large output currents are required to support heavy load operation.
One conventional approach to implementing a voltage regulator, such as a synchronous buck converter, includes utilizing a pulse-width modulation (PWM) scheme to control the buck converter output stage. That approach typically results in good operating efficiency under heavy and medium load conditions. However, use of PWM to control buck converter output is associated with significant efficiency degradations as load conditions become light, due to switching loss, conduction loss, and/or transistor gate driving loss, for example.
The disadvantages associated with light load operation of a PWM controlled buck converter may have been tolerable when electronic devices were operated according to a classical binary ON/OFF paradigm. In that operating environment, an electronic device or system was completely shut down when not in use, e.g., it was turned OFF, and affirmatively turned ON only when needed, e.g., typically to operate at a medium or heavy load condition. As electronic devices and systems have become more pervasively integrated into almost all aspects of everyday life, however, the use of electronics in an always or mostly ON state in which load conditions may vary widely has grown increasingly common. Moreover, because many of those always or mostly ON electronic devices are likely to spend much of their operating time in a standby, or reduced power mode during which light load conditions prevail, light load efficiency has become increasingly important. Light load efficiency is also a significant concern for battery operated portable electronic devices, which are typically configured to revert to a power saving standby mode when not actively in use.
Thus, there is a need to overcome the drawbacks and deficiencies in the conventional art by a buck converter configured to be responsive to the demands of a variable load while providing high efficiency across a spectrum of operating conditions including light load conditions and heavy load conditions.